1. Technical Field
The disclosure relates to light emitting diode lamps, and particularly to a control circuit for maintaining a luminous intensity of a light emitting diode lamp within an acceptable range.
2. Description of Related Art
Recently, light emitting diodes (LEDs) have become widely used in a variety of LED lamps, for example, miner's lamps, street lamps, submarine lamps and stage lamps, for their low power requirement and long lifetime.
The LED lamps may be used in an environment whose brightness level changes at different time periods, so that the LED lamp needs to output light with different light intensities to satisfy the lighting needs. If the brightness level of the environment surrounding the LED lamp is weaker, the luminous intensity of the LED lamp needs to be increased; otherwise the luminous intensity of the LED lamp needs to be decreased to save electric energy. However, the conventional LED lamp can only emit light with a constant luminous intensity, but can not spontaneously change intensity of light output in response to the brightness level of the environment surrounding the LED lamp.
It is thus desirable to provide an LED lamp with a control circuit which can overcome the described limitations.